Patients with cardiovascular disease are increasing in association with the aging society. In cardiovascular disease, early detection and follow-up in treatment are important as well as other diseases, and periodic examination of cardiovascular function is needed.
In cardiovascular disease, morbidity of atrial fibrillation increases along with aging. An epidemiological study shows that the prevalence thereof increases sharply over the age of 70, and it reaches 4% to 8% in 70's, and reaches 10% in 80's. Further, it has been indicated that patients with atrial fibrillation have a high risk of left atrial thrombi which may flow out from the heart and occlude cerebral vessels to thereby cause cardioembolic stroke. Accordingly, by means of positive use of anticoagulants for preventing cardioembolic stroke in recent years, treatment of embolism associated with atrial fibrillation has been improved dramatically.
On the other hand, in patients with atrial fibrillation, heart rhythm is irregular and tachycardia often occurs, which decreases the cardiac output and worsens the cardiac function. Accordingly, in order not to worsen the cardiac condition, a treatment for controlling the irregular heart rate appropriately has been performed. However, the results of a mega-scale clinical trial demonstrated that there were no differences in life prognosis between a group of patients in which the heart rate was strictly controlled less than 80 per minute and a group of patients in which the heart rate was controlled in a non-strict manner less than 110 per minute. Then, it is considered to be meaningless to give treatment to a patient with atrial fibrillation by using heart rate as an index. Nowadays, medical treatment is given based on symptoms complained by a patient such as palpitation, a feeling of dyspnea, and a feeling of fatigue.
As patients with atrial fibrillation are increasing along with the rapid aging of society, patients with dementia are also increasing. Further, it has been reported that patients with atrial fibrillation have a risk of dementia about 1.4 times. In such a situation, it is considered to be problematic to give treatment based on only symptoms complained by elderly patients. This also applies to pediatric patients who are not able to explain symptoms accurately. Thus, it has been required to objectively perform diagnosis, medical treatment, and follow-up by using a cardiac function index which is an essential index for treatment of atrial fibrillation, instead of a therapeutic strategy based on subjective symptoms complained by a patient.